1. Field of the Invention
This invention relates to a wrist and forearm exercise apparatus more particularly to a wrist and forearm exercise apparatus with a resistance adjustment device.
2. Description of the Related Art
The improvement of this invention is directed to the conventional wrist and forearm exercise apparatus shown in FIG. 1. As illustrated, the conventional exercise apparatus includes an annular forearm support unit 1, a grip assembly 2 and a resistance adjustment device 3. The forearm support unit 1 includes a curved upper plate 1a, a curved lower plate 1b integrally formed with the upper plate 1a, a tubular body 1c secured to the upper plate 1a and which has a central bore 1d, an opening 1e formed through the front end wall of the tubular body 1c, and an externally threaded rear end portion 1f. The grip assembly 2 includes a pivot portion 2a mounted pivotally on the forearm support unit 2b, a grip portion 2b located at the front end portion of the grip assembly 2, and a pull portion 2c located at the rear end portion of the grip assembly 2. The resistance adjustment device 3 includes a spring accommodating tube 3a with a slide slot 3a formed at the front end portion thereof, a sliding piece 3b disposed slidably in the spring accommodating tube 3, an externally threaded movable inner tube 3c disposed within the spring accommodating tube 3a and provided with a radial guide pin 3c' slidable in the slide slot 3a' so as to prevent rotation of the inner tube 3c relative to the spring accommodating tube 3a, a cord 3d with a rear end fastened to the sliding piece 3b, and a front end coupled with the grip assembly 2, a coiled compression spring 3e disposed within the spring accommodating tube 3a and sleeved on the cord 3e between the sliding. piece 3b and the inner tube 3c, and an adjustment ring 3f.
As shown in FIG. 1A, the adjustment ring 3f has a small-diameter threaded hole 31f engaging threadably the inner tube 3c, and a large-diameter threaded hole 32f engaging threadably the threaded rear end portion if of the tubular body 1c. When it is desired to adjust the resistance to the swinging movement of the grip assembly 2 on the forearm support unit 1, the adjustment ring 3f is rotated on the tubular body 1c so as to move the inner tube 3c within the spring accommodating tube 3c, thus compressing the spring 3e to a selected extent. However, it is difficult to control the adjusted amount of the compression of the spring 3e due to the stepless adjustment of the ring 3f.